The present invention relates generally to an airbag apparatus provided with an airbag that is expanded upon collision of a vehicle for protecting an occupant and, more specifically, to an airbag apparatus provided with an airbag including a left airbag section and a right airbag section which are expanded separately on the left and right sides in front of the occupant. The present invention also relates to a method of folding an airbag.
As an airbag for protecting an occupant upon collision of a vehicle or the like, an airbag having a left airbag section and a right airbag section that are expanded separately on the left and right sides in front of an occupant and are expanded by a common inflator is disclosed in Japanese Unexamined Patent Application Publication No. 4-292239 (incorporated by reference herein in its entirety). In the airbag of the same publication, the distal ends of the left airbag section and the right airbag section are connected by a tie panel.
This airbag is folded and stored in a case, and wrapped by a cover. When the inflator (gas generator) is activated and injects gas upon collision of the vehicle, the airbag is expanded in front of the occupant while pushing and opening the cover.
This inflator is disposed inside or outside of the airbag on the proximal side. In the airbag apparatus having a structure in which the inflator is disposed outside the airbag on the proximal side, injected gas of the inflator is supplied to the airbag via a gas inlet port provided on the proximal side of the airbag.
When arranging the inflator inside the airbag on the proximal side, the entire inflator may be arranged inside the airbag, or part of the inflator may be arranged inside the airbag. As an example of the latter case, there is a structure in which the airbag is formed with a pair of slit-shaped openings, a rod-shaped inflator is inserted into the slit-shaped openings, and both ends of the inflator are projected outside the airbag.
In the airbag disclosed in the above-described Japanese Unexamined Patent Application Publication No. 4-292239, since the distal ends of the left airbag section and the right airbag section are connected by the tie-panel, when the airbag is expanded, the tie panel receives the lateral center of the occupant's body.
In the airbag disclosed in the above-described Japanese Unexamined Patent Application Publication No. 4-292239, when the left airbag section and the right airbag section are expanded, gas from the inflator may flow more into one of the airbags, whereby expansion of the other airbag may be delayed in comparison with the one airbag.
In the airbag of the same patent publication, since the left airbag section and the right airbag section are connected by the tie panel, even when expansion of one of the airbags is delayed, it is expected that the previously expanded airbag pulls the airbag whose expansion is delayed in the direction of expansion via the tie panel and promotes its expansion. However, since the left airbag section and the right airbag section are connected to each other at the distal ends thereof, the previously expanded airbag cannot pull the airbag whose expansion is delayed via the tie panel sufficiently until the previously expanded airbag is expanded to the distal end.
In the airbag having the left airbag section and the right airbag section as disclosed in the above-described Japanese Unexamined Patent Application Publication No. 4-292239, if the capacities of the left airbag section and the right airbag section after expansion are significant, an inflator having a large capacity is required for inflating the airbag quickly.